Synaptic Transmission - Biological Psychology [AQA ALevel]

Summary

This video explains synaptic transmission, the process by which neurons communicate using neurotransmitters. It covers how electrical impulses travel through neurons, how neurotransmitters are released across the synapse, and how they influence the postsynaptic cell. The video also delves into summation, the role of excitatory and inhibitory neurotransmitters, and the impact of psychoactive drugs like SSRIs and cocaine. Additionally, it highlights the astonishing complexity of the brain's synaptic connections, emphasizing the vast number of synapses and their essential role in human consciousness and memory.

Takeaways

• 😀 The synapse is a tiny gap between two neurons where chemical transmission of signals occurs, allowing communication in the brain.
• 😀 Action potentials (electrical impulses) travel down the axon of the presynaptic neuron and trigger the release of neurotransmitters into the synapse.
• 😀 Neurotransmitters are chemicals that carry signals across the synaptic cleft to the postsynaptic neuron.
• 😀 The postsynaptic neuron has receptors that detect neurotransmitters and initiate a response, either exciting or inhibiting the cell.
• 😀 Excitatory neurotransmitters depolarize the postsynaptic neuron, making it more likely to fire an action potential.
• 😀 Inhibitory neurotransmitters hyperpolarize the postsynaptic neuron, making it less likely to fire an action potential.
• 😀 Summation refers to the process where the effects of excitatory and inhibitory signals are combined to determine if the postsynaptic neuron will fire.
• 😀 If the postsynaptic cell reaches its threshold after summation, it will generate a new action potential that continues the signal down the axon.
• 😀 Reuptake is the process by which neurotransmitters are taken back into the presynaptic neuron, resetting the synapse for the next signal.
• 😀 Psychoactive drugs like SSRIs and cocaine alter neurotransmitter transmission, either increasing or inhibiting the reuptake of chemicals like serotonin and dopamine.

Q & A

What is the synapse and why is it important in biological psychology?

The synapse is the junction where two neurons almost touch, and it plays a crucial role in transmitting information between neurons using chemical signals called neurotransmitters. It is essential in understanding how information is passed through the body and how psychoactive drugs influence the brain.

How does an electrical impulse travel along a neuron?

The electrical impulse, known as an action potential, travels down the axon of a neuron, eventually reaching the axon terminal. However, this electrical impulse cannot directly cross the synapse, so it is converted into a chemical signal via neurotransmitters.

What happens at the axon terminal during synaptic transmission?

At the axon terminal, an action potential triggers vesicles to merge with the membrane of the presynaptic neuron, releasing neurotransmitters into the synaptic cleft. These neurotransmitters then travel across the gap to the postsynaptic neuron.

What is the function of neurotransmitters in synaptic transmission?

Neurotransmitters act as chemical messengers that carry signals across the synaptic cleft. They bind to receptors on the postsynaptic neuron, influencing its electrical charge. This can either make the neuron more likely to fire an action potential (excitatory) or less likely (inhibitory).

What is the difference between excitatory and inhibitory neurotransmitters?

Excitatory neurotransmitters make the postsynaptic neuron more positive, increasing the likelihood of an action potential forming. Inhibitory neurotransmitters make the neuron more negative, decreasing the likelihood of an action potential.

What is summation in the context of synaptic transmission?

Summation is the process where the effects of all excitatory and inhibitory neurotransmitter signals on the postsynaptic cell are added or subtracted. If the overall effect reaches a certain threshold, a new action potential is triggered in the postsynaptic neuron.

Why is the communication in synaptic transmission unidirectional?

Communication is unidirectional because the neurotransmitters are released from the presynaptic neuron and detected by receptors on the postsynaptic neuron. The process is designed for one-way signaling, ensuring efficient transmission of information.

What happens to neurotransmitters after they bind to receptors?

After neurotransmitters bind to receptors on the postsynaptic neuron, they detach. Some neurotransmitters are broken down, while others are recycled back into the presynaptic neuron through a process called reuptake, preparing the system for the next signal.

How do certain psychoactive drugs affect synaptic transmission?

Psychoactive drugs can interfere with synaptic transmission by either inhibiting or increasing the transmission of neurotransmitters. For example, SSRIs block the reabsorption of serotonin, increasing its levels in the synapse, while cocaine blocks dopamine reuptake, enhancing its signal.

How many synapses are in the average human brain, and what is their significance?

An average human brain has around 170 trillion synapses. These synapses play a key role in processing information and forming the basis for consciousness, memories, and experiences. The vast number of synapses demonstrates the immense complexity of the brain's communication system.